1. Field of the Invention
The present invention relates to a direct cylinder injection-type spark ignition internal combustion engine.
2. Description of the Prior Art
There has heretofore been known to produce stratified charge combustion by directly injecting the fuel into the cylinder to form a mixture in the vicinity only of a spark plug at the ignition timing to burn a lean mixture in the cylinder as a whole. To carry out the stratified charge combustion, in general, the fuel injection valve is opened for only a period required for injecting a required amount of fuel from a crank angle for starting the fuel injection set in the latter half of the compression stroke. It is intended that the thus injected fuel proceeds into a concave combustion chamber formed in the top surface of the piston and is deflected toward the spark plug, due to the shape of the combustion chamber, while being vaporized after robbing heat from the wall surface of the combustion chamber in order to form a mixture that can be favorably ignited near the spark plug.
In general, the fuel injection valve injects fuel in a form that is conically concentrated. Therefore, a relative long period is required while the fuel injected in the last stage of fuel injection becomes a combustible mixture utilizing the heat from the wall surface of the combustion chamber. To ensure this period, therefore, the fuel-injection end timing must be advanced. An amount of fuel which can be injected in the latter half of the compression stroke, therefore, inevitably decreases, and the stratified charge combustion must be abandoned in high engine load operations in which a relatively large amount of fuel is required. It has therefore been desired to carry out stratified charge combustion, which is effective in decreasing the consumption of fuel, over a wide range of engine operation conditions.
Japanese Unexamined Patent Publication (Kokai) No. 9-158736 proposes injecting the fuel in the shape of a flat fan having a relatively small thickness by using a fuel injection valve having an injection hole in the shape of a slit. The thus injected fuel can rob heat from a wide area of the wall surface of the combustion chamber, making it possible to form a combustible mixture within a short period and to retard the timing for ending the injection of fuel. It is therefore possible to increase an amount of fuel injected in the latter half of the compression stroke and to expand the region of stratified charge combustion toward the high engine load side.
According to the prior art as described above, even if the timing for ending the injection of fuel is retarded, a combustible mixture can be reliably formed from the injected fuel at an ignition timing. The thus formed combustible mixture has a flat shape with its length being shorter than the width thereof and rises nearly in the direction of the length. The ignition timing must occur while the combustible mixture is rising and is coming in contact with the spark plug. However, the combustible mixture has a relatively short length and stays contacted to the spark plug while it is rising for only a relative short period. Therefore, it may often happen that the combustible mixture has already passed over the spark plug at the ignition timing due to a slight deviation in the timing for forming the combustible mixture, and the reliable ignition performance is not maintained.
The object of the present invention therefore is to reliably maintain the ignition performance and to reliably expand the region of the stratified charge combustion toward the high engine load side in a direct cylinder injection-type spark ignition internal combustion engine in which the fuel is injected in the form of a flat fan having a relative small thickness.
According to the present invention, there is provided a first direct cylinder injection-type spark ignition internal combustion comprising a spark plug, a cavity formed in the top surface of a piston, and a fuel injection valve for injecting fuel into the cavity in nearly the shape of a fan having a relatively small thickness, wherein, when the fuel injected in nearly the shape of a fan from the fuel injection valve is considered by being divided into a plurality of fuel segments in a radial direction, a side wall of the cavity has a first fuel deflection passage and a second fuel deflection passage for deflecting at least two of the plurality of fuel segments to pass near the spark plug, the side wall of the cavity is at least partly provided with a return portion that protrudes toward the inside of the cavity, the first fuel deflection passage is not provided with the return portion or is provided with the return portion having a short protrusion, and the second fuel deflection passage is provided with the return portion having a long protrusion.
According to the present invention, there is provided a second direct cylinder injection-type spark ignition internal combustion engine comprising a spark plug, a cavity formed in the top surface of a piston, and a fuel injection valve for injecting fuel into the cavity in nearly the shape of a fan having a relatively small thickness, wherein, when the fuel injected in nearly the shape of a fan from the fuel injection valve is considered as being divided into a plurality of fuel segments in a radial direction, a side wall of the cavity has a first fuel deflection passage and a second fuel deflection passage for deflecting at least two of the plurality of fuel segments to pass near the spark plug, the side wall of the cavity is at least partly provided with an arcuate portion having an arcuate shape in cross section in the vertical direction, and a radius of curvature of the arcuate shape of said arcuate portion on said first fuel deflection passage is larger than that of said arcuate portion on said second fuel deflection passage.
According to the present invention, there is provided a third direct cylinder injection-type spark ignition internal combustion engine comprising a spark plug, a cavity formed in the top surface of a piston, and a fuel injection valve for injecting fuel into the cavity in nearly the shape of a fan having a relatively small thickness, wherein, when the fuel injected in nearly the shape of a fan from the fuel injection valve is considered as being divided into a plurality of fuel segments in a radial direction, a side wall of the cavity has a first fuel deflection passage and a second fuel deflection passage for deflecting at least two of the plurality of fuel segments to pass near the spark plug, the side wall of the cavity is at least partly provided with a return portion that protrudes toward the inside of the cavity, the side wall of the cavity inclusive of the return portion has an arcuate shape in cross section in the vertical direction, the first fuel deflection passage is not provided with the return portion or is provided with the return portion having the shortest protrusion, a radius of curvature of the arcuate shape of the first fuel deflection passage is the greatest, and the first fuel deflection passage is closest to the spark plug.
According to the present invention, there is provided a fourth direct cylinder injection-type spark ignition internal combustion engine comprising a spark plug, a cavity formed in the top surface of a piston, and a fuel injection valve for injecting fuel in nearly the shape of a fan having a relatively small thickness so that the fuel collides with a bottom wall of the cavity at an acute angle, wherein, when the fuel injected in nearly the shape of a fan from the fuel injection valve is considered as being divided into a plurality of fuel segments in a radial direction, the bottom wall of the cavity has a plurality of neighboring fuel leading passages for leading the plurality of fuel segments collided toward the side wall of the cavity, the side wall of the cavity has a first fuel deflection passage and a second fuel deflection passage for deflecting at least two of the plurality of fuel segments led by the plurality of fuel leading passages to pass near the spark plug, and the angle of collision of the fuel in a first fuel leading passage among the plurality of fuel leading passages for leading the fuel segment to the first fuel deflection passage, is smaller than the angle of collision of the fuel in a second fuel leading passage among the plurality of fuel leading passages for leading the fuel segment to the second fuel deflection passage.
According to the present invention, there is provided a fifth direct cylinder injection-type spark ignition internal combustion engine comprising a spark plug, a cavity formed in the top surface of a piston, and a fuel injection valve for injecting fuel in nearly the shape of a fan having a relatively small thickness so that the fuel collides with a bottom wall of the cavity at an acute angle, wherein, when the fuel injected in nearly the shape of a fan from the fuel injection valve is considered as being divided into a plurality of fuel segments in a radial direction, the bottom wall of the cavity has a plurality of neighboring fuel leading passages for leading the plurality of fuel segments collided toward the side wall of the cavity, the side wall of the cavity has a first fuel deflection passage and a second fuel deflection passage for deflecting at least two of the plurality of fuel segments led by the plurality of fuel leading passages to pass near the spark plug, and the depth near the side wall of the cavity in a first fuel leading passage among the plurality of fuel leading passages for leading the fuel segment to the first fuel deflection passage, is smaller than the depth near the side wall of said cavity in a second fuel leading passage among the plurality of fuel leading passages for leading the fuel segment to the second fuel deflection passage.
According to the present invention, there is provided a sixth direct cylinder injection-type spark ignition internal combustion engine comprising a spark plug, a cavity formed in the top surface of a piston, and a fuel injection valve for injecting fuel in nearly the shape of a fan having a relatively small thickness so that the fuel collides with a bottom wall of the cavity at an acute angle, wherein, when the fuel injected in nearly the shape of a fan from the fuel injection valve is considered as being divided into a plurality of fuel segments in a radial direction, the bottom wall of the cavity has a plurality of neighboring fuel leading passages for leading the plurality of fuel segments collided toward the side wall of the cavity, the side wall of the cavity has a plurality of fuel deflection passages for deflecting all of the plurality of fuel segments led by the plurality of fuel leading passages to pass near the spark plug, and the lengths in the plurality of fuel leading passages from positions where the fuel collides to points of a predetermined depth of the cavity gradually change.
According to the present invention, there is provided a seventh direct cylinder injection-type spark ignition internal combustion engine comprising a spark plug, a cavity formed in the top surface of a piston, and a fuel injection valve for injecting fuel in nearly the shape of a fan having a relatively small thickness so that the fuel collides with a bottom wall of the cavity at an acute angle, wherein, when the fuel injected in nearly the shape of a fan from the fuel injection valve is considered as being divided into a plurality of fuel segments in a radial direction, the bottom wall of the cavity has a plurality of neighboring fuel leading passages for leading the plurality of fuel segments collided toward the side wall of the cavity, the side wall of the cavity has a first fuel deflection passage and a second fuel deflection passage for deflecting at least two of the plurality of fuel segments led by the plurality of fuel leading passages to pass near the spark plug, concave or convex resisting portions of a predetermined number are formed on at least one of the second fuel deflection passage and a second fuel leading passage among the plurality of fuel leading passages for leading the fuel segment to the second fuel deflection passage, and the resisting portions of a number smaller than the predetermined number are formed on at least one of the first fuel deflection passage and a first fuel leading passage among the plurality of fuel leading passages for leading the fuel segment to the first fuel deflection passage, or the resisting portions are formed on neither the first fuel deflection passage nor the first fuel leading passage.
According to the present invention, there is provided a eighth direct cylinder injection-type spark ignition internal combustion engine comprising a spark plug, a cavity formed in the top surface of a piston, and a fuel injection valve for injecting fuel in nearly the shape of a fan having a relatively small thickness so that the fuel collides with a bottom wall of the cavity at an acute angle, wherein, when the fuel injected in nearly the shape of a fan from the fuel injection valve is considered as being divided into a plurality of fuel segments in a radial direction, the bottom wall of the cavity has a plurality of neighboring fuel leading passages for leading the plurality of fuel segments collided toward the side wall of the cavity, the side wall of the cavity has a first fuel deflection passage and a second fuel deflection passage for deflecting at least two of the plurality of fuel segments led by the plurality of fuel leading passages to pass near the spark plug, a first resisting portion of a concave shape having a predetermined depth or of a convex shape having a predetermined height is formed on at least one of the second fuel deflection passage and a second fuel leading passage among the plurality of fuel leading passages for leading the fuel segment to the second fuel deflection passage, and a second resisting portion of a concave shape having a depth smaller than the predetermined depth or of a convex shape having a height smaller than the predetermined height is formed on at least one of the first fuel deflection passage and a first fuel leading passage among the plurality of fuel leading passages for leading the fuel segment to the first fuel deflection passage, or the first resisting portion is formed on neither the first fuel deflection passage nor the first fuel leading passage.
According to the present invention, there is provided a ninth direct cylinder injection-type spark ignition internal combustion engine comprising a spark plug, a cavity formed in the top surface of a piston, and a fuel injection valve for injecting fuel in nearly the shape of a fan having a relatively small thickness so that the fuel collides with a bottom wall of the cavity at an acute angle, wherein, when the fuel injected in nearly the shape of a fan from the fuel injection valve is considered as being divided into a plurality of fuel segments in a radial direction, the bottom wall of the cavity has a plurality of neighboring fuel leading passages for leading the plurality of fuel segments collided toward the side wall of the cavity, the side wall of the cavity has a first fuel deflection passage and a second fuel deflection passage for deflecting at least two of the plurality of fuel segments led by the plurality of fuel leading passages to pass near the spark plug, and a plurality of guide protuberances are formed on the bottom surface of the cavity to define a first fuel leading passage among the plurality of fuel leading passages for leading the fuel segment to the first fuel deflection passage and a second fuel leading passage among the plurality of fuel leading passages for leading the fuel segment to the second fuel deflection passage, the plurality of guide protuberances being nearly in a linear form, and the angle of deflection of the fuel segment in the first fuel leading passage being smaller than the angle of deflection of the fuel segment in the second fuel leading passage.
According to the present invention, there is provided a tenth direct cylinder injection-type spark ignition internal combustion engine comprising a spark plug, a cavity formed in the top surface of a piston, and a fuel injection valve for injecting fuel in nearly the shape of a fan having a relatively small thickness so that the fuel collides with a bottom wall of the cavity at an acute angle, wherein, when the fuel injected in nearly the shape of a fan from the fuel injection valve is considered as being divided into a plurality of fuel segments in a radial direction, the bottom wall of the cavity has a plurality of neighboring fuel leading passages for leading the plurality of fuel segments collided toward the side wall of the cavity, the side wall of the cavity has a plurality of fuel deflection passages for deflecting all of the fuel segments led by the plurality of fuel leading passages to pass near the spark plug, and a plurality of guide protuberances are formed on the bottom surface of the cavity to define the plurality of fuel leading passages, the plurality of guide protuberances being nearly in a linear form and nearly in parallel with a plane that passes through the center of the injection hole of the fuel injection valve and the center of the cavity.
According to the present invention, there is provided a eleventh direct cylinder injection-type spark ignition internal combustion engine comprising a spark plug, a cavity formed in the top surface of a piston, and a fuel injection valve for injecting fuel in nearly the shape of a fan having a relatively small thickness so that the fuel collides with a bottom wall of the cavity at an acute angle, wherein, when the fuel injected in nearly the shape of a fan from the fuel injection valve is considered as being divided into a plurality of fuel segments in a radial direction, the bottom wall of the cavity has a plurality of neighboring fuel leading passages for leading the plurality of fuel segments collided toward the side wall of the cavity, the side wall of the cavity has a first fuel deflection passage and a second fuel deflection passage for deflecting at least two of the plurality of fuel segments led by the plurality of fuel leading passages to pass near the spark plug, and a plurality of guide protuberances are formed on the bottom surface of the cavity to define a first fuel leading passage among the plurality of fuel leading passages for leading the fuel segment to the first fuel deflection passage from a second fuel leading passage among the plurality of fuel leading passages for leading the fuel segment to the second fuel deflection passage, the plurality of guide protuberances being in a curved form, and the center lines in the first fuel leading passage and in the second fuel guide passage defined by the plurality of guide protuberances have such shapes that a radius of curvature of the center line of the first fuel leading passage is larger than a radius of curvature of the center line of the second fuel leading passage or the center line of the first fuel leading passage is straight.
According to the present invention, there is provided a twelfth direct cylinder injection-type spark ignition internal combustion engine comprising a spark plug, a cavity formed in the top surface of a piston, and a fuel injection valve for injecting fuel into the cavity in nearly the shape of a fan having a relatively small thickness, wherein the cavity has a side wall for deflecting all the fuel to pass near the spark plug, and a plurality of deflection guide protuberances are formed in the cavity to deflect the fuel in the direction of width thereof.
According to the present invention, there is provided a thirteenth direct cylinder injection-type spark ignition internal combustion engine comprising a spark plug, a cavity formed in the top surface of a piston, and a fuel injection valve for injecting fuel in nearly the shape of a fan having a relatively small thickness so that the fuel collides with a bottom wall of the cavity at an acute angle, wherein the fuel that has collided with the bottom wall of the cavity travels toward the side wall of the cavity along the bottom wall, the side wall of the cavity deflects the whole fuel that has arrived at the side wall to pass near the spark plug, and the bottom wall of the cavity is inclined from one side end of the fuel travelling on the bottom wall toward the other side end thereof.
According to the present invention, there is provided a fourteenth direct cylinder injection-type spark ignition internal combustion engine comprising a spark plug, a cavity formed in the top surface of a piston, and a fuel injection valve for injecting fuel in nearly the shape of a fan having a relatively small thickness so that the fuel collides with a bottom wall of the cavity at an acute angle, wherein the fuel that has collided with the bottom wall of the cavity travels toward the side wall of the cavity along the bottom wall, and a vertical plane at the center of the side wall of the cavity in a range at where the fuel arrives intersects a vertical plane at the center of the fuel at a predetermined angle.
According to the present invention, there is provided a fifteenth direct cylinder injection-type spark ignition internal combustion engine comprising a spark plug, a cavity formed in the top surface of a piston, a means for forming a swirl that rotates in a cylinder in nearly the horizontal direction, and a fuel injection valve for injecting fuel into the cavity in nearly the shape of a fan having a relatively small thickness, wherein the cavity has a side wall for deflecting all the fuel to pass near the spark plug, and a protruding portion is formed on the top surface of the piston corresponding to at least the side wall of the cavity over a range for deflecting the fuel.
According to the present invention, there is provided a sixteenth direct cylinder injection-type spark ignition internal combustion engine comprising a spark plug, a cavity formed in the top surface of a piston, and a fuel injection valve for injecting fuel into the cavity in nearly the shape of a fan having a relatively small thickness, wherein the cavity has a side wall for deflecting all the fuel to pass near the spark plug, and a squish area is formed on the top surface of the piston to generate a squish that travels chiefly in the direction of width of the fuel to pass near the spark plug.
According to the present invention, there is provided a seventeenth direct cylinder injection-type spark ignition internal combustion engine comprising a spark plug, a cavity formed in the top surface of a piston, and a fuel injection valve for injecting fuel into the cavity in nearly the shape of a fan having a relatively small thickness, wherein a squish area is formed on the top surface of the piston to generate a squish that travels chiefly toward the fuel injection valve from the side opposing the fuel injection valve to pass near the spark plug, and a plurality of stepped portions are formed in the cavity, which portions are successively collided with by the fuel injected from the fuel injection valve accompanying the rise of the piston, at least two of the stepped portions which are collided with by the fuel, when an amount of fuel injected is small, deflect the collided fuel, in parallel, toward the upstream side of the squish beyond the spark plug.
According to the present invention, there is provided a eighteenth direct cylinder injection-type spark ignition internal combustion engine comprising a spark plug and a fuel injection valve for directly injecting fuel into the cylinder, wherein the fuel injected from the fuel injection valve passes near the spark plug directly or after being deflected, and the injection rate of the fuel injection valve is decreased in the last stage of fuel injection.
According to the present invention, there is provided a nineteenth direct cylinder injection-type spark ignition internal combustion engine comprising a spark plug and a fuel injection valve for directly injecting fuel into the cylinder, wherein the fuel injected from the fuel injection valve passes near the spark plug directly or after being deflected, and a crank mechanism has the center of the crank shaft deviated from the center axis of the piston so that the angular speed of the crank is lowered in the compression stroke.